[diss] Insinööritieteiden korkeakoulu / ENG

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3D geovisualizations in human-centered quality assessments of urban and green spaces — from point clouds to nonabsolute spaces
(Aalto University, 2022) Jaalama, Kaisa; Hyyppä, Hannu, Dr., Aalto University, Finland; Fagerholm, Nora, Prof., University of Turku, Finland; Rakennetun ympäristön laitos; Department of Built Environment; Geoinformatics; Insinööritieteiden korkeakoulu; School of Engineering; Vaaja, Matti T., Prof., Aalto University, Department of Built Environment, Finland
Through technological advancement, vertical, three-dimensional (3D) geoinformation has been designated to fulfil the horizontal, two-dimensional data resources and viewpoint of the environment. However, 3D geovisualizations are still divergent and unstandardized. This also applies to our understanding of their impact on society—their ability to imitate their physical counterparts as a lived environment and places as a social entity. While a range of studies presents solutions and applications for 3D geovisualizations, fewer focus on their critical examination in human-centered urban and green space assessments in an interdisciplinary way. This dissertation contributed to filling this gap by presenting three case studies conducted with 3D geovisualizations. First, the role of 3D point cloud data acquisition was tested for objective-deductive urban green assessments with a green factor framework. Second, the applicability of 3D geovisualizations was tested for subjective-inductive assessments in terms of perceived affordances of an urban park deck, using in-situ-based interview data as a reference in the analysis of the virtual reality-based interview data. Third, the role of subjective place relations with perceived realism (i.e., sense of presence) and subjective place meanings (i.e., sense of place) in subjective-inductive assessments with 3D geovisualizations was demonstrated. Finally, a framework presenting distinct knowledge approaches with 3D geovisualizations was reconciled.The results show that design for data capture is an interplay of the respective framework, individual characteristics of the physical properties, measurement devices, and additional information sources available. Future frameworks for assessment tasks, such as green efficiency in cities, should be designed to include the possibilities of vertical strata and volume. Further, the results show that most of the dimensions of green space affordances were at least to some extent perceivable in a subjective-inductive assessment through 3D geovisualization. Compared to the in-situ interview data, challenges with 3D geovisualization were linked to the weaker perception of surroundings outside the park deck, lack of social clues, and deficits in visual detail and coherency. The results underline the perception-altering role of prior familiarity with the geovisualized place both for the sense of presence and sense of place. Visual realism and spatial presence can enforce the communicative effectiveness of 3D geovisualizations, but so can prior familiarity with the place. The results demonstrate that, apart from objective-deductive methods, urban and green space planning can benefit from subjective-inductive assessments with 3D geovisualizations. A central outcome is that 3D geovisualization possesses possibilities for distinct knowledge approaches that contribute to each other in a co-productive manner.
The 4th P - people - in urban development based on Public-Private-People Partnership
(Teknillinen korkeakoulu, 2008) Majamaa, Wisa; Rakenne- ja rakennustuotantotekniikan laitos
The topic and the scope of this dissertation is the inclusion of the end-users' perspective into Public-Private Partnership (PPP) based urban development processes. The examined and developed 4P-based urban development process is by its nature a strategic Public-Private-People Partnership (4P) of local government and public land owners (Public), developers and private land owners (Private), and end-users (People) for good living environment and separate customer relationships. The empirical study is based on communicative planning theory and on a theory of rational consumers. Also a residential choice and an innovation theory - where end-users are the primary stakeholders in the innovation process - are discussed in this study. The qualitative study includes two levels of PPP-based urban development process. A general level of urban development process in its early stages - planning and design - and a more detailed level - purchasing process of PPP-based real estate service delivery projects. The research methods used in this study are multiple case study and action research. The dissertation found that the inclusion of the end-users' perspective in the PPP-based, or, more likely, in the 4P-based urban development processes is both possible and rewarding. The results show that it is possible to identify and categorise the end-users' perspective in a more detailed level of PPP-based urban development process, i.e. in a real estate service delivery, and to transfer the knowledge to the general level of PPP-based urban development process. It is also argued that the developed 4P-based urban development process increases the participation of the potential end-users, and creates a new kind of end-user orientated knowledge for the process. Engaging the end-users in development processes opens previously unseen potential for including consumerist possibilities for cities and developers. In this context, the 4P-based urban development process has created possibilities for engaging new pro-active and positive participation methods and solutions, not only for the early stages of urban development process (planning and design), but also for construction, operation and management of local economic and social infrastructure. The more concrete practical value and implication of this dissertation is the developed framework to include end-users' perspective into purchasing process of 4P-based real estate service delivery projects.
Accomplishing rural electrification for over a billion people: Approaches towards sustainable solutions
(Aalto University, 2014) Rahman, Mizanur Md.; Paatero, Jukka, Dr., Aalto University, Department of Energy Technology, Finland; Energiatekniikan laitos; Department of Energy Technology; Energy Economics and Power Plant Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, Finland
Access to electricity appears to be a prerequisite to materialize social, economic, and human development in the underprivileged rural areas. However, 1.1 billion rural people in the world, almost all of them living in developing countries, still do not have access to electricity. Although the rural electrification process poses more challenges than urban electrification, rural areas are blessed with abundant and relatively evenly distributed renewable energy resources. To facilitate electricity access to this huge population, it is essential to deal with the rural electrification task by considering its challenging features and the potential merits of renewable resources. The objective of this thesis is to present policy and techno-economic frameworks for sustainable and accelerated rural electrification for over a billion people in developing countries. This thesis considers grid expansion as the primary option for rural electrification, and renewable resource based off-grid options were considered as the alternative where grid expansion is not feasible. Grid-based rural electrification policies were examined by focusing on one case program (the Bangladesh rural electrification program) in light of challenges that are generic for developing countries. The assessment of the potentials and techno-economic viability of renewable resources were performed by utilizing analytical methodologies and well-established computer tools (HOMER and RETScreen). The evaluation of choices among rural electrification alternatives has been illustrated with the help of the Stochastic Multicriteria Acceptability Analysis (SMAA) tool. The evaluation methods and tools are illustrated by employing case data obtained mainly from Bangladesh. This thesis observed that some key policy elements influence the performance of a grid-based rural electrification program. These policy elements guide the rural electrification program towards success through addressing distinct rural electrification challenges. Agricultural residues have the potential to generate electricity to meet household-level demands in rural areas of many developing countries. Hybrid biogas and solar resources can serve both clean-cooking and electricity loads in rural households with achieving benefit (saving) more than the cost. The multicriteria decision support technique enables a rural electrification program to choose decision options from different alternatives based on sustainability criteria.
Adapting Nordic Buildings for Enhanced Summertime Resilience in the Face of Climate Change
(Aalto University, 2024) Velashjerdi Farahani, Azin; Jokisalo, Juha, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Heating, Ventilation and Air conditioning; Insinööritieteiden korkeakoulu; School of Engineering; Kosonen, Risto, Prof., Aalto University, Department of Mechanical Engineering, Finland
In the face of escalating climate change impacts, understanding the resilience of buildings to extreme weather events, particularly in cold climates, is crucial for mitigating risks to human thermal comfort and well-being. This thesis addresses this issue by investigating the resilience of different buildings to climate change and its associated hot summers in Nordic climates. Through a combination of field measurements and simulation studies, the research assesses indoor overheating risks, energy consumption, and power demand in different building types, while also exploring the relationship between indoor and outdoor temperatures during heatwaves. The findings reveal significant challenges posed by high overheating risks in residential buildings, particularly in older ones in comparison to the newer ones designed based on the latest building codes. The study highlighted the effectiveness of passive strategies in mitigating risks. However, results showed that there is a need for mechanical cooling systems in residential buildings to ensure comfortable and healthy indoor temperatures during current and future heat events. The needed cooling electricity was shown to be considerably small compared to other energy consumptions in the buildings. Additionally, the study identifies strong correlations between indoor and outdoor temperatures during the hot summers that weakened during the prolonged heatwaves. This highlights the complex and dynamic nature of these relationships under different environmental conditions and emphasizes the importance of considering extreme heat events in the design and operation of buildings in cold climates. In office buildings, all-air and air-water systems were found to perform equally in terms of cooling energy consumption and indoor temperature conditions under a changing climate. While the maximum cooling power demand would be higher with the all-air system (ventilative) during extreme weather conditions. However, the cooling electricity increased up to 47% in the future average climate and up to 128% in the future extreme climate with the air-water system, and up to 51% in the future average climate and 108% in the future extreme climate with the all-air system by 2050 depending on the CO2 emission scenario.
Advancements of operational oceanography in the Baltic Sea
(Aalto University, 2019) Roiha, Petra; Tuomi, Laura, Dr., Finnish Meteorological Institute, Finland; Rakennetun ympäristön laitos; Department of Built Environment; Insinööritieteiden korkeakoulu; School of Engineering; Koivusalo, Harri, Prof., Aalto University, Department of Built Environment, Finland
Managing the sea environment is a complicated interdisciplinary task. To understand changes in the sea, knowledge of the present state is essential. Many variables are monitored constantly, and long historical data sets exist. However, the spatial and temporal data coverage varies widely over the Baltic Sea. The preparation for the emerging circumstances demands the ability to forecast the future marine conditions. Thus, improved modelling and forecasting systems are needed. In this thesis, methods were developed to 1) understand the present state of the sea and 2) predict future conditions. The study areas were the Bothnian Sea and the Eastern Gotland Basin. Argo floats are a common tool in the oceans, but so far they have not been used in shallow marginal seas, such as the Baltic Sea. The autonomous measurement device brings possibilities to fill the gaps in the existing observation network (e.g. research vessels, moorings) as well as to enable new scientific experiments. To better understand the present state of the Northern Baltic Sea, methods were developed using the Argo floats. The salinity, temperature and GPS data collected with these floats from the area is analysed in this thesis for the first time and its applicability for studying the different physical phenomena, such as currents at the float diving depth and wind induced mixing, are evaluated. The usability of Argo data was compared with the ship-borne CTD data. Due to the higher frequency of the Argo data, the seasonal variations can be studied in detail with this method. However, the spatial coverage of the Argo data is not as good as the CTD data collected with a research vessel due to the fact that the floats only operate near the deep areas of the Baltic Sea. To be able to predict the future conditions of the Baltic Sea, monthly ensemble forecasting system was developed. A 3D biogeochemical model was forced with monthly ensembles of the atmospheric forcing and the results were applied to forecast upwelling events and harmful algal blooms. The monthly ensemble forecasts for upwelling events were evaluated. The result was that the upwelling events could be forecasted on a weekly scale. This enables, for example, better planning of the scientific study of upwelling events or the improvement of local-scale weather forecasts. The same probability-based ensemble prediction system was used to produce harmful algal bloom forecasts. The forecasts showed the effects of the weather scenarios on marine biogeochemistry. In the future, it will be possible to interconnect the observations and forecasts better than before. The more dense observations can be used to improve the computational methods, for example, by assimilation. The probability-based forecasts can help, for example, to mitigate the environmental risks.
Advances in Humidity Measurement Applications in Metrology
(Aalto University, 2015) Sairanen, Hannu; Heinonen, Martti, Dr., VTT Technical Research Centre of Finland, Finland; Energiatekniikan laitos; Department of Energy Technology; Applied Thermodynamics; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, Finland
A significant part of the development of humidity measurement applications in metrology is carried out due to the climate change. Within this thesis metrology tools for humidity measurements in energy gases were developed. In addition, a new method and apparatus for radiosonde calibrations were developed and constructed to provide traceability to the System of Units (SI) and thus improve the quality of radiosonde measured humidity data. Metrology tools for humidity measurements of energy gases were developed by studying the water vapour enhancement factor for methane. A new hygrometer-based calibration method was developed and a set-up was assembled for calibrations of liquid microflows from syringepumps. Metrological validation for the set-up including uncertainty analysis was carried outfor flow rates from 0.1 ul min-1 to 10 ul min-1. The set-up was applied in development and construction of a novel apparatus to measure the enhancement factor. The apparatus was metrologically validated by air and methane measurements for pressures up to 6 MPa and dew/frost-point temperatures from -50 °C to +15 °C. Utilising this apparatus, new experimental enhancement factor data was measured. Along with literature data on equilibrium states of water vapour in methane, new literature-based enhancement factors were calculated. The experimental and the calculated data were combined and an equation expressed as a function of pressure and dew-pointe temperature was fitted to the data. The equation covers dew/frost-point temperature range from -23 °C to +20 °C and pressures below 7 MPa and its expanded uncertainty (k = 2) is 0.23 in the whole range. Radiosondes operate over a wide range of humidity, temperature and pressure values and thus their calibrations should also cover these conditions. However, calibrations performed with traditional methods at cold temperatures and low humidity require a lot of time and therefore a customized apparatus was developed and constructed. The new apparatus enables significantly shorter calibration times within the temperature range from -80 °C to +20 °C and the dew/frost-point temperature range between -90 °C and +10 °C. The apparatus fulfils the requirements set by Global Climate Observing System (GCOS) and its GCOS Reference Upper-Air Network (GRUAN).
Advancing design criteria for energy and environmental performance of buildings
(Aalto University, 2018) Jung, Nusrat; Airaksinen, Miimu, Dr., Finnish Association of Civil Engineers, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy technology; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Mechanical Engineering, Finland
Globally, buildings are responsible for 18% of greenhouse gas (GHG) emissions and 40% of energy consumption. The European Union’s climate and energy policy framework for 2020 and 2030 requires reducing GHG emissions by 40%, increasing the level of energy savings by 25%, and increasing the share of renewable energy by at least 30% relative to 1990. The environmental and energy performance criteria for buildings will continually evolve to meet the aforementioned decarbonisation goals. Consequently, buildings will have an increased number of variables and alternatives that are to be evaluated for their performance, indicating increased complexity for building designers. The prospect of evaluating multiple building performance criteria necessitates integrated designing and planning tools, such as the use of Building Information Model (BIM), Building Performance Simulations (BPS), and methodologies for comparing and optimizing alternative design options. This dissertation presents new insights on advancing the design criteria for the energy and environmental performance of commercial and residential buildings. Specially, the four associated journal publications demonstrate how building designers and the Architecture, Engineering, and Construction (AEC) industry can integrate embodied GHG analysis, comprehensive BIM tools in conjunction with BPS analyses, and stochastic assessment of public perceptions to work towards buildings that are more energy-efficient, generate energy on-site, and have a smaller carbon footprint. Through comprehensive literature reviews, this dissertation outlines future research directions for BIM-based, iterative multi-criteria assessment for energy and environmental performance of buildings.
Advancing safety in autonomous shipping through modern hazard analysis methods - A System-Theoretic Approach
(Aalto University, 2023) Chaal, Meriam; Bahootoroody, Ahmad, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Safe and Efficient Marine and Ship Systems; Insinööritieteiden korkeakoulu; School of Engineering; Valdez Banda, Osiris A., Prof., Aalto University, Department of Mechanical Engineering, Finland
The maritime industry is currently undergoing a substantial transformation towards autonomous shipping, where human involvement in operational activities is diminishing, emphasizing safety and efficiency improvements. This transition, however, introduces new safety challenges that necessitate rigorous risk assessment and innovative safety frameworks. This thesis commences with an exploration of the historical development of risk, safety, and reliability considerations in autonomous shipping through a bibliometric review. Additionally, the future research directions and the potential risk assessment methods adequate for the complex autonomous ships are analysed. System Theoretic Process Analysis (STPA) is a key focus of this study. The thesis provides and investigate a model of the STPA organizational control structure within the maritime operational paradigm, seeking to reveal safety challenges of the transition to autonomy. An essential aspect of the work presented in this thesis involves integrating STPA with established marine risk assessment procedures, utilizing Bayesian Networks to quantify risks. The proposed framework scrutinizes the selection of Risk Control Options (RCOs) within Marine Risk Assessment (MRA) process and examines the potential incorporation of STPA-BN within the Formal Safety Assessment (FSA) process. Drawing upon conventional maritime practices, the thesis offers an approach to develop safety control structure of autonomous ship systems and provides an analysis of the control structure components of Autonomous Navigation Systems (ANS). Hence identifies unique safety challenges posed by these innovations. In summary, this doctoral thesis serves as a technical compass guiding the maritime industry towards enhanced safety in the age of autonomous shipping. By leveraging modern hazard analysis methods, particularly STPA, and integrating them into established risk assessment practices, this research seeks to catalyse a shift towards advanced system-theoretic risk assessment processes in the maritime industry, acknowledging the evolving regulatory landscape and the complexity of the challenges at hand.
Advancing sustainable transformation of cities - An analysis of city and household level efforts in the pursuit of carbon-neutrality targets
(Aalto University, 2020) Ahvenniemi, Hannele; Häkkinen, Tarja, Dr., VTT Technical Research Centre of Finland, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Kosonen, Risto, Prof., Aalto University, Department of Mechanical Engineering, Finland
It has been widely recognised that cities and particularly the built environment have a major role in fighting against climate change. Acknowledging the challenge, city governments have been eager to declare ambitious carbon-neutrality targets along with smart city strategies. Simultaneously academia and the business sector have announced a number of measures and solutions as to how these targets can be reached. However, a commonly accepted definition on smart cities – and an understanding of the link to sustainable cities – is still lacking. High expectations are also faced by households, major contributors of cities' greenhouse gas emissions, who are expected to be motivated to adopt smart and sustainable measures and understand the significance of them. This dissertation composes of five individual studies examining the topic 'Advancing sustainable transformation of cities' from various angles and on both city and household levels. The first part of the dissertation focuses on the target setting of cities, studying 1) the similarities and differences of smart and sustainable city targets, and 2) how cities express their environmental sustainability targets in their strategies. The second part of the dissertation deals with the household level, studying the environmental impacts and economic benefits of sustainability measures implemented by households, as well as other motivational factors behind sustainable choices. The results of the publications show that advancing environmental sustainability efficiently on both city and household levels may be challenging. When cities aim for 'smartness', they do not automatically pursue environmental sustainability. It seems that remarkable efforts are still needed to incorporate environmental sustainability targets of cities to an all-compassing action plan. When households implement carbon mitigating actions, these actions may not always lead to efficient results, nor do they necessarily provide economic benefits. Forerunner households who have implemented renewable energy technologies however report other type of benefits: they experience pleasure from energy self-sufficiency and being able to share information, among others. Information is crucial regarding households' efforts to cut carbon by implementing actions, and smart technologies may play a key role here. While smartness targets have become pervasive – bringing along technologies and measures to speed up sustainable transformation – it is essential for cities to clarify which of the smart measures truly are useful in regard of environmental sustainability goals.
Advancing the Lead User Method and its Adoption in Organizations
(Aalto University, 2016) Helminen, Pia; Hyysalo, Sampsa, Associate Prof., Aalto University, Department of Design, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Ekman, Kalevi, Prof., Aalto University, Department of Mechanical Engineering, Finland
A key to being a successful business is not only being able to respond to demand but being able to anticipate future demand. This is easier said than done, as understanding what users need is one of the areas of most persistent and costly failure in product development. The importance of involving users in the development of both products and services has been widely noted, but some users develop solutions on their own. This is not a marginal phenomenon, but innovation by users and so called lead users can be found in all fields ranging from post-it-notes to sporting equipment and surgical instruments to banking services, for example. The lead user method is described as a process that companies could apply in their product or service development in order to benefit from lead users. Despite its documented advantages, the LU method has not gained ground as a standard part of companies' toolbox for product and service development. In this dissertation, a qualitative approach building on semi-experimental set-ups, a multiple case study, and a longitudinal two-case case study was used to explore the challenges involved in the use of the LU method and to provide remedy and direction for its use in organizations that are seeking to benefit from lead users. First, this dissertation improves the concepts and means available for lead user identification. Second, it generates more understanding on and alternative means for transferring the lead user knowledge. Third, it sheds light on the factors that challenge the adoption of the LU method in an organization and provides suggestions on how the adoption hurdles could be overcome. It was found that instead of general resistance to user ideas or new ways of working or the cost and time required by the LU method, it is the difficulty of transferring and retaining the knowledge of how to conduct a LU project that hinders its adoption in an organization. The case analyses demonstrate that the LU method features skill components that are more costly and difficult (i.e. "sticky") to transmit among employees than the adopter organizations were prepared for. Rather ironically, it is the same phenomenon that user innovation research has identified as one of the key reasons for why users hold solution and trend information and why lead users should be utilized in the first place.
Aging of Iron-Based Martensites at Low Temperatures
(Helsinki University of Technology, 1992) Ullakko, Kari; Laboratory of Engineering Materials; Insinööritieteiden korkeakoulu; School of Engineering; Pietikäinen, Juha; Hänninen, Hannu
In the present work aging of iron-based martensites, defined as all the phenomena preceding the first stage of tempering, is studied using various methods. In some alloys aging was observed to start at very low temperatures, even near 4 K. Abnormally high or abnormally low tetragonality is observed in freshly formed martensite alloyed with Ni or Mn, respectively. The reason for high tetragonality obviously lies in the coherency at the interface between the martensite and the retained austenite. It is shown in the present work that the coherency is broken during aging in the temperature range of 100 - 200 K and it is accompanied by a decrease of tetragonality (first stage of aging). The new internal friction peak centered at 145 K corresponds to the movement of the coherent interface and the break of coherency. Some evidence for correlation between short range atomic ordering in austenite and the high tetragonality of the virgin martensite is given and a contribution of nontransformed ordered austenitic regions inside martensite plates to tetragonality is discussed. It is shown that the second stage of aging at temperatures about 200 - 270 K is controlled by the pinning of the dislocations by carbon atoms and the third stage (mainly above 250 K) by the clustering of carbon atoms in a solid solution. By means of Mössbauer spectroscopy, electrical resistivity and magnetic susceptibility measurements, a striking difference is shown between the redistribution of carbon and nitrogen atoms above 200 K. Evidence for the clustering of carbon and ordering of nitrogen is given and discussed. The dynamics of clustering was studied by means of small angle neutron scattering. Deformation of martensite at subambient temperatures reduced the tetragonality of martensite to cubic and changed the redistribution of carbon atoms. According to different measurements, practically no aging was observed below room temperature in the deformed martensite.
Algorithmic Advancements in Drive-by Inspection Methods Towards Intelligent Bridge Monitoring
(Aalto University, 2023) Lan, Yifu; Rakennustekniikan laitos; Department of Civil Engineering; Bridge Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Lin, Weiwei, Assoc. Prof., Aalto University, Department of Civil Engineering, Finland
Since conventional vibration-based structural health monitoring (SHM) methods typically require the installation of numerous sensors directly onto the bridge, the substantial costs associated with on-site sensor installation and maintenance have long rendered such technology an expensive option. Recently, an alternative approach referred to as the "drive-by bridge inspection method" has attracted scholarly attention. This method necessitates no instrumentation on the bridge; instead, it uses a few sensors positioned on the vehicle traversing the bridge, with the vehicle functioning as both an exciter and a receiver. It offers the possibility to efficiently monitor groups of bridges (particularly small and medium-sized ones), presenting an economically efficient solution to bridge health monitoring problems. While previous research on the drive-by method has yielded promising results, there are still some challenging problems and ample room for improvement before its engineering application. This thesis aims to propose algorithmic solutions to address the challenges faced by the current drive-by methods, successfully extracting bridge modal parameters and identifying damage. In terms of bridge modal parameters, two algorithms are proposed. Algorithm 1 extracts the bridge frequency as a common signal component in the responses of multiple sensors mounted on the vehicle. This method does not require specially designed vehicles or multiple cars, as in earlier studies, but instead utilizes a single ordinary vehicle, providing a practical solution. Algorithm 2 employs the Coherence-PPI (Prominent Peak Identification) method, which extracts the bridge frequency from the common vibrational components of multiple passes of the same vehicle. Rather than seeking to minimize differences, it encourages variability in drive-by measurements (e.g., varying vehicle parameters, avoiding traversing the same road surface) to filter bridge frequencies. It is particularly suitable for vehicles passing the same bridge multiple times (such as buses). In terms of damage identification, a data-driven algorithm based on an optimized AdaBoost-linear SVM is proposed (Algorithm 3), which accurately indicates bridge damage using only the raw vibration signals received from vehicles passing the bridge. To further improve damage identification accuracy and address certain limitations of drive-by measurements, such as noise and data redundancy, a time-domain signal processing algorithm for the raw vehicle accelerations is also proposed (Algorithm 4). The proposed algorithms have been validated through numerical simulations, laboratory experiments, and field tests on simply supported and continuous beam bridges using truck and bus models. The ultimate goal is to achieve a practical and intelligent bridge health monitoring system.
Alternative Fuels and Emission Control Methods in Compression Ignition Engines
(Aalto University, 2019) Tilli, Aki; Sarjovaara, Teemu, Dr., Neste, Finland; Kaario, Ossi, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Conversion; Insinööritieteiden korkeakoulu; School of Engineering; Larmi, Martti, Prof., Aalto University, Department of Mechanical Engineering, Finland
The focus of this doctoral thesis is on the effect of alternative diesel fuels on engine performance, emissions, and emission reduction technologies in diesel engines. The studies focused on normal engine operation, enhanced engine parameters for biofuel use, and on modern aftertreatment technologies. The research included engine experiments, simulations, and optical studies. Especially hydrotreated vegetable oil (HVO) and its blends were studied. For comparison, standard EN590 fulfilling regular diesel and its blends with traditional biodiesel (FAME) were also investigated. FAME and HVO represent different biofuel generations. FAME is a first generation biofuel with typically small-scale production and varying product quality. It consists of oxygen-containing esters not found in pure fossil diesel. Additionally, FAME has lower energy content. The maximum amount of FAME is 7% in standard EN590. HVO is a second generation biofuel with typically large-scale production and high quality. HVO consists of paraffinic hydrocarbons - compounds found also in regular diesel. High proportions of HVO can typically be used in diesel engines without any modifications. The first part of this thesis involves biofuels and their effects on medium-speed diesel engine performance and emissions. The biofuels were evaluated with simulations, and the effects of 100% HVO on engine performance and emissions were investigated with engine experiments. Internal exhaust gas recirculation (iEGR) and Miller timing were studied with regular diesel and HVO. The latter part of the thesis focuses on late post-injections (LPI) with 30% blends of HVO and FAME, used for diesel particulate filter (DPF) regeneration in an off-road diesel engine. During the LPI mode, exhaust gas temperature rise in the diesel oxidation catalyst (DOC), emissions, and oil dilution were investigated. Additionally, the corresponding fuel sprays were investigated in optical engines. With 100% HVO, the compatibility, performance and emissions were first investigated with no engine parameter changes. With Miller timing and iEGR, the high ignitability lead to significant nitrogen oxide (NOx) decrease, with no fuel consumption or particulate matter (PM) emission increase. In contrast to the typical NOx-PM -trade-off, both emissions were lowered. In the LPI studies, no drawbacks were found with 30% HVO blend. 30% FAME blend resulted in worse oil dilution related to LPI's, and increased emissions during the LPI mode. No significant differences in the LPI spray lengths were measured between the fuels. Thus, the differences in the oil dilution were contributed to the distillation characteristics of the fuels.
Amplifying Unheard Voices - Towards Inclusive Innovation and Development
(Aalto University, 2024) van der Marel, Floris; Konetekniikan laitos; Department of Mechanical Engineering; Swinburne University of Technology; Insinööritieteiden korkeakoulu; School of Engineering; Björklund, Tua, Prof., Aalto University, Department of Mechanical Engineering, Finland; Kocsis, Anita, Prof., Swinburne University of Technology, Australia
An increasingly diverse engineering workforce supports innovation and creativity. However, whether diversity translates to improved organisational performance depends on whether employees are able to voice issues and ideas. Voice is conceptualised as employees' ability to speak up and be heard. While much research has been done by industrial relations, human resource management, and organisational behaviour scholars, their different ontological assumptions have made it difficult to integrate the learnings. As such, much is still unknown about how socioorganisational factors influence employee voice, particularly in a more diverse workforce. Building on existing literature, I argue that motivation at work and assessment of voice opportunities are key indicators of employees' resolution to voice or not. Both work motivation and voice opportunity assessment are influenced by collaborative sensemaking and former voicing attempts. In this dissertation, I dive deeper into the nuance and intricacies that influence diverse employees' experiences in creative contexts. Based on semi-structured interviews with 130 designers, engineers, and hospital employees targeting job motivation and voice opportunity assessments, I identify patterns across different contexts that might apply to other contexts worldwide. One study applies an action research approach, teaching design to the hospital employees to shed light on changed perceptions and frames as a result of a participatory design intervention. Each study highlights the highly social context of creativity and innovation, influenced by continuous interactions with people around them. Indeed, my results suggest that both motivation and voice opportunity assessment were influenced by stubborn beliefs present in collaborative sensemaking, disproportionately impacting historically unheard voices. Additionally, spirals of silence might hinder attempts to amplify unheard voices due to ingrained silence as a result of previous failed attempts by employees similar to them. In conclusion, I argue that more attention should be paid to the role of collaborative sensemaking in employee voice in order to leverage diverse voices toward inclusive innovation and development.
Analysing landmarks in nature and elements of geospatial images to support wayfinding
(Finnish Geodetic Institute, 2014) Kettunen, Pyry; Sarjakoski, Tiina, Prof., Finnish Geodetic Institute, Department of Geoinformatics and Cartography, Finland; Maankäyttötieteiden laitos; Department of Real Estate, Planning and Geoinformatics; Finnish Geodetic Institute, Department of Geoinformatics and Cartography, Finland; Geodeettinen laitos, Geoinformatiikan ja kartografian osasto; Insinööritieteiden korkeakoulu; School of Engineering; Virrantaus, Kirsi, Prof., Aalto University, Department of Real Estate, Planning and Geoinformatics, Finland
This dissertation applies the research and methods of spatial cognition in order to contribute to the development of wayfinding support in geospatial applications. The design and development of geospatial applications, such as interactive maps and mobile navigation applications, has been typically founded on the expertise of surveying, cartography and geoinformatics. This has often led to relatively complex expert tools that many users find difficult to use. The research of spatial cognition can provide elementary understanding about human thinking in the use situations of these applications and supplement the knowledge gained using the usability research. Perception of landmarks along routes in nature was studied in season and time-of-day studies with participants who walked nature trails in summer, winter, day and night while thinking aloud about the surroundings. The recall of the route was measured afterwards using sketch-map drawing and photo recognition tasks. The think-aloud protocols were analysed using classification of propositions and natural language processing. The importance of landmarks for the human route perception in nature was confirmed. "Structures", "Passages" and "Waters" were the most perceived landmark groups. Season and time-of-day significantly affected landmark perception and, based on the results, the adaptivity of geospatial applications in the studied conditions can be improved. The transfer of the empirically acquired knowledge of the landmark perception to geoinformatics was illustrated with a formal landmark ontology for hiking in nature. The measures of landmark recall were found unexpectedly similar in all the studied conditions. The similarity was explained by the salience of landmarks in nature and the structure of route-like sketch maps but also by the participants' conceptions on what should be drawn on maps. "Passages" and "Structures" were the most-often drawn landmark groups on the sketch maps. Support of geospatial images for wayfinding was evaluated using a literature-based evaluation framework. Visualisation of elevation was experimented with by rendering a 3D map, a derivative of which was compared to 2D elevation visualisations in an eye-tracking study. Vertical elements and elevation were found to be central wayfinding elements in geo-images and the aerial oblique vantage point the most effective image parameter for transferring spatial knowledge. The rendered 3D map was evaluated as cognitively demanding to look at but, however, showed potential in representing the terrain relief. The dissertation also considers challenges in the application of the methods of spatial cognition research and identifies directions for future studies.
Analysis of inorganic nitrogen leaching in a boreal river basin in northern Finland
(Helsinki University of Technology, 2006-03-24) Rankinen, Katri; Department of Civil and Environmental Engineering; Rakennus- ja ympäristötekniikan osasto; Laboratory of Water Resources; Vesitalouden ja vesirakennuksen laboratorio
In this study the dynamic, semi-distributed INCA-N model was applied to the boreal Simojoki river basin in northern Finland to outline inorganic nitrogen (N) leaching patterns and N processes in catchment scale. Special emphasis was paid to the quality assurance of the modelling work. The dominant human impacts in the area are forestry, agriculture, scattered settlement and atmospheric deposition. In order to assess the effectiveness of current environmental policies and to implement river basin management plans, it is essential to know the relative significance of the different sources of pollution. INCA-N explained main features of the hydrological pattern and seasonality of inorganic N concentrations in river water when N processes in soil in sub-zero temperatures were included. Over-winter N mineralization processes in soil accounted for 38% of annual N mineralization. The lowest concentrations during the growing season were not reproduced, which indicates that there are some retention processes missing from the model. As summer is typically a low flow period the simulation results are reliable as long as the interpretation is based on daily or annual loads. Loading from the river basin was mostly dependent on annual hydrology and it was concentrated to peaks during the snow melting period. In the upper parts of the river inorganic N load originated mainly from commercial forests. At the outlet of the river anthropogenic sources accounted for more than half of the overall inorganic N load, with agriculture, forestry and scattered settlements making almost equal contributions. Expected changes in atmospheric N deposition would not have any significant effect but the combination of water protection measures both in agricultural and forestry areas and in scattered settlement areas would decrease inorganic N load by 18% of the total load. The expected increase in forest felling of 20% would not have an influence, but increase in agricultural land due to the EU's Common Agricultural Policy might lead to increased N load to the sea.
An analysis of the effect of ultrasonic burnishing on surface integrity
(Aalto University, 2018) Huuki, Juha; Laakso, Sampsa, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Engineering Design and Production; Insinööritieteiden korkeakoulu; School of Engineering; Aaltonen, Kalevi, Prof., Aalto University, Department of Mechanical Engineering, Finland
Modern manufacturing processes require high surface quality output. The growing requirements products have to meet are creating the perception that surface finishing processes are often an essential process in meeting product specifications. Surface finishing methods play a key role in achieving strict quality and tolerance requirements. Burnishing is a process which produces a fine surface finish on a workpiece and commonly applied to improve the surface integrity, i.e. surface roughness, residual stress and hardness of a mechanical components. Burnishing has long been used in the automotive industry to finish a wide variety of car and heavy equipment components. Ultrasonic burnishing is a modern, effective method for improving surface quality. The method is based on forging the surface of the workpiece at an ultrasonic frequency with more than 20,000 impacts per second. However, in order to investigate how the method affects the surface quality of the material, a better understanding of surface integrity is required. The aim of this study was to find out how the ultrasonic burnishing method affects the surface integrity and form: surface roughness, hardness, residual stresses and out-of-roundness and diameter changes in different material surfaces. The research analysed the characteristics of the ultrasonic burnishing method of surface finishing, in particular by means of experiments, and its impacts on metal parts made of different materials. The results were evaluated to investigate the optimal process parameters for AM-material. In conclusion, the outcomes of this study show that ultrasonic burnishing improves the surface integrity effectively. The method was found to be highly suitable for finishing different materials, such as AM produced metal components, according to the results of the experiments in this study. The findings show, that method not only affects the top surface efficiently, but also deforms the material more deeply, producing compressive residual stresses in the workpiece. Furthermore, the roundness of a cylindrical workpiece is improved and the dimensional changes are minor. These improvements are achieved without long processing times from the point of view of the resulting surface quality. The conclusions of the dissertation indicate that ultrasonic burnishing is a fast, simple and economical finishing process that provides an improved surface quality and hardness. To this end, future research is proposed on the capabilities the method offers on workpieces with diverse contours, such as finishing double-curved surfaces. In addition, further research is recommended to find the optimal burnishing process parameters with different types of AM materials. Furthermore, the results of this study encourage the greater use of ultrasonic burnishing in diverse industrial fields, which will provide added opportunities for research in the future.
Analytical analyses of active control of sound transmission through soft-core sandwich structures and double panel partitions
(Aalto University, 2016) Sahu, Kiran Chandra; Reddy, J. N., Prof., Texas A & M University, USA and Aalto University, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Applied Mechanics; Insinööritieteiden korkeakoulu; School of Engineering; Tuhkuri, Jukka, Prof., Aalto University, Department of Mechanical Engineering, Finland
Active structural acoustic control (ASAC) is a form of active noise control which focuses on the control of structural vibrations in a manner that minimizes acoustic radiation from a structure. The greatest difficulty ASAC suffers from is in finding an "optimal" error quantity, which can be easily implemented in a control algorithm. Volume velocity control (VVC) metric which is generally used in ASAC typically requires either a large number of sensors distributed across the entire structure, or a single distributed shaped sensor. A new parameter termed "weighted sum of spatial gradients (WSSG)" showed a great potential to significantly reduce noise transmission using four sensors only. This thesis carried out a comprehensive study on VVC and WSSG, and numerical calculations indicate that, by intelligent selection of modal indices for the calculation of WSSG and the frequency band of active control, WSSG is able to achieve comparable amount of sound attenuation with VVC. Soft-core sandwich panels are increasingly used because of their high strength-to-weight ratios. However, acoustical properties of these are less desirable at low frequencies, which can lead to high noise levels. Since additional sound absorbing materials fail to provide satisfactory results at low frequencies, active control techniques have been researched. It is very well known that soft-core sandwich panels vibrate in flexural modes (occur at low frequencies) and dilatational modes (occur in high frequencies). Therefore, in this thesis, VVC and WSSG control metrics are used to control these modes in order to achieve control in a broader frequency band. Numerical studies illustrate that the control metrics are able to attenuate both modes and increase the sound transmission loss irrespective of isotropic core loss factors. In buildings, windows are often the weak link in protecting the interior from outside noise. In particular, double panel windows have a poor sound insulation at low frequencies around the mass-air-mass resonance. Sound absorbing materials in the air gap fail to provide satisfactory results in the low-frequency region, therefore, an active controller is an attractive approach to reduce the noise level in buildings. This thesis used the WSSG control metric to drive piezoelectric actuators in order to attenuate the dipole-type of motion of double panel systems, a motion that commonly occurs at high frequencies. Thereby, sound attenuation in a large frequency band can be accomplished. Also, acoustic point source arrangements are considered between the panels. Numerical results indicate that the actuator should be placed on the incident panel to minimize the control quantities on the radiating panel, and combined WSSG and cavity control is able to provide better sound attenuation in a wider frequency band.
Analyzing electricity market efficiency and impacts of renewable electricity
(Aalto University, 2022) Farsaei, Anahita; Syri, Sanna, Prof., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Efficiency and Systems; Insinööritieteiden korkeakoulu; School of Engineering; Syri, Sanna, Prof., Aalto University, Department of Mechanical Engineering, Finland
The EU aims to be climate-neutral by 2050. Achieving net-zero greenhouse gas emissions needsaction in all economic sectors including electricity markets. Electricity market is experiencing a rapid transition to renewable energy especially in the Nordic countries. Although the growing amount of renewables paves the path for climate change mitigation, their effect on market efﬁciency needs to be studied. Furthermore, in an interconnected multi-national electricity market, local energy policies in one country can affect the other countries. This dissertation examines these possible effects. This dissertation analyses market power potential in the Iranian electricity market as well as in Finland and in the Baltic countries. A new Lerner index is proposed for the pay-as-bid auction. Lerner index and HHI are employed for Finland and the Baltic countries. In addition, the impacts of local energy policies in Finland and Sweden on the neighboring countries are studied in this dissertation. Finland has implemented legislation to phase out coal by 2029. In Sweden, there is an ongoing debate regarding nuclear power. Different scenarios are proposed in this dissertation to analyze the effect of these policies on average electricity prices, CO2 emissions, electricity system cost and electricity trade in Finland, Sweden and the Baltic countries. For this purpose, the models Enerallt and REX are employed to model short-term and long-term future with low CO2 emissions. In the short-term, coal and peat in Finland are replaced with biomass while for 2050, a growing amount of wind power is employed. International transmission expansion is also considered in scenarios for 2050. The results indicate that in Iran market power potential increases during off-peak hours. In Finland, HHI and Lerner index values show that increasing wind power in the electricity market mostly results in less market power potential. However, for the Baltic countries despite the signiﬁcant entrance of wind power in electricity market, they have a highly concentrated market. Results from analyzing the effects of local policies in interconnected markets on the neighboring countries show that national-level policies have impact on wider regions. In the short-term, phasing out coal in Finland may lead to increased electricity import from the wider Nordic market area and even outside it, mostly from regions with carbon-intensive generation. With this policy, among the studied countries only Finland will face a decrease in CO2 emissions in the region, while the rest of the countries will see a small increase. However, the long-term transition to very low CO2 emissions from the electricity production can beneﬁt the Baltic countries. International transmission expansion by 2050 can provide the Baltic countries with an opportunity to have electricity sufﬁciency and export more electricity. Achieving this needs signiﬁcant new investments in wind power capacity.
API-based Digital Twins - Architecture for Building Modular Digital Twins Following Microservices Architectural Style
(Aalto University, 2021) Ala-Laurinaho, Riku; Konetekniikan laitos; Department of Mechanical Engineering; Mechatronics; Insinööritieteiden korkeakoulu; School of Engineering; Tammi, Kari, Assoc. Prof., Aalto University, Department of Mechanical Engineering, Finland
The Fourth industrial revolution drives the rapid digitalization of industry. Digital twin is an emerging tool for digitalization and offers various features, such as simulations, predictive maintenance, and optimization of operation. These features are highly use case dependent, and at simplest, a digital twin may only be a metadata document of the physical product. Because digital twins and their use cases vary greatly, creating an architecture that covers most of the digital twin features has been proven to be challenging. The digital twin features could be partly implemented using existing systems, but the current architectures do not employ these systems to the full extent. This dissertation proposes an Application Programming Interface (API)-based digital twin architecture for creating modular digital twins and presents a proof-of-concept implementation of the architecture for an overhead crane. The architecture enables using existing systems to implement digital twin and makes the digital twin data available from a single interface. In the API-based digital twin architecture, digital twins consist of separate software blocks that implement the features of digital twins and can work in collaboration. Each block offers its services via API that is accessed via Data Link. Data Link acts as a message broker between the blocks and makes their services available on the Internet. The practical implementation of the broker is an API gateway, which forwards HTTP (Hypertext Transfer Protocol) messages to software blocks. This API-based architecture follows microservices architectural style, in which each software block is responsible for implementing one feature of a digital twin. This study also compares Web APIs, REST (Representational State Transfer) and GraphQL, for industrial communication. These interfaces can be used to connect microservices to Data Link. In addition, the suitability of Web APIs for an additional interface to an OPC UA (Open Platform Communications Unified Architecture) server is investigated. OPC UA can provide access to an industrial machine PLC (Programmable Logic Controller) system. Finally, Open Sensor Manager (OSEMA) is presented as an enabler for data collection from a physical entity, which helps to keep a digital twin in sync with its counterpart. OSEMA allows remote software updates of sensors nodes and makes adding new ones easy by generating software based on the node configuration. In conclusion, this thesis presented a general API-based architecture for digital twins. The proposed architecture makes digital twin data accessible, provides a platform for creating advanced applications, and allows the use of existing systems to build digital twins. In addition, the architecture is flexible, modular, and scalable. This thesis also compared Web interfaces, which allow connecting microservices to Data Link, in industrial communication and presented one microservice for a digital twin. This service is Open Sensor Manager that facilitates keeping digital twin sync with its counterpart. These contributions aid in the digitalization of industry and accelerate the Fourth industrial revolution.

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